1 /****************************************************************************
2  * Copyright (c) 1998-2007,2008 Free Software Foundation, Inc.              *
3  *                                                                          *
4  * Permission is hereby granted, free of charge, to any person obtaining a  *
5  * copy of this software and associated documentation files (the            *
6  * "Software"), to deal in the Software without restriction, including      *
7  * without limitation the rights to use, copy, modify, merge, publish,      *
8  * distribute, distribute with modifications, sublicense, and/or sell       *
9  * copies of the Software, and to permit persons to whom the Software is    *
10  * furnished to do so, subject to the following conditions:                 *
11  *                                                                          *
12  * The above copyright notice and this permission notice shall be included  *
13  * in all copies or substantial portions of the Software.                   *
14  *                                                                          *
15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS  *
16  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF               *
17  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.   *
18  * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,   *
19  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR    *
20  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR    *
21  * THE USE OR OTHER DEALINGS IN THE SOFTWARE.                               *
22  *                                                                          *
23  * Except as contained in this notice, the name(s) of the above copyright   *
24  * holders shall not be used in advertising or otherwise to promote the     *
25  * sale, use or other dealings in this Software without prior written       *
26  * authorization.                                                           *
27  ****************************************************************************/
28 
29 /****************************************************************************
30  *  Author: Zeyd M. Ben-Halim <zmbenhal@netcom.com> 1992,1995               *
31  *     and: Eric S. Raymond <esr@snark.thyrsus.com>                         *
32  *     and: Thomas E. Dickey                        1996-on                 *
33  ****************************************************************************/
34 
35 /*-----------------------------------------------------------------
36  *
37  *	lib_doupdate.c
38  *
39  * 	The routine doupdate() and its dependents.
40  * 	All physical output is concentrated here (except _nc_outch()
41   *	in lib_tputs.c).
42  *
43  *-----------------------------------------------------------------*/
44 
45 #include <curses.priv.h>
46 
47 #if defined __HAIKU__ && defined __BEOS__
48 #undef __BEOS__
49 #endif
50 
51 #ifdef __BEOS__
52 #undef false
53 #undef true
54 #include <OS.h>
55 #endif
56 
57 #if defined(TRACE) && HAVE_SYS_TIMES_H && HAVE_TIMES
58 #define USE_TRACE_TIMES 1
59 #else
60 #define USE_TRACE_TIMES 0
61 #endif
62 
63 #if HAVE_SYS_TIME_H && HAVE_SYS_TIME_SELECT
64 #include <sys/time.h>
65 #endif
66 
67 #if USE_TRACE_TIMES
68 #include <sys/times.h>
69 #endif
70 
71 #if USE_FUNC_POLL
72 #elif HAVE_SELECT
73 #if HAVE_SYS_SELECT_H
74 #include <sys/select.h>
75 #endif
76 #endif
77 
78 #include <ctype.h>
79 #include <term.h>
80 
81 MODULE_ID("$Id: tty_update.c,v 1.246 2008/08/30 20:08:19 tom Exp $")
82 
83 /*
84  * This define controls the line-breakout optimization.  Every once in a
85  * while during screen refresh, we want to check for input and abort the
86  * update if there's some waiting.  CHECK_INTERVAL controls the number of
87  * changed lines to be emitted between input checks.
88  *
89  * Note: Input-check-and-abort is no longer done if the screen is being
90  * updated from scratch.  This is a feature, not a bug.
91  */
92 #define CHECK_INTERVAL	5
93 
94 #define FILL_BCE() (SP->_coloron && !SP->_default_color && !back_color_erase)
95 
96 static const NCURSES_CH_T blankchar = NewChar(BLANK_TEXT);
97 static NCURSES_CH_T normal = NewChar(BLANK_TEXT);
98 
99 /*
100  * Enable checking to see if doupdate and friends are tracking the true
101  * cursor position correctly.  NOTE: this is a debugging hack which will
102  * work ONLY on ANSI-compatible terminals!
103  */
104 /* #define POSITION_DEBUG */
105 
106 static NCURSES_INLINE NCURSES_CH_T ClrBlank(WINDOW *win);
107 static int ClrBottom(int total);
108 static void ClearScreen(NCURSES_CH_T blank);
109 static void ClrUpdate(void);
110 static void DelChar(int count);
111 static void InsStr(NCURSES_CH_T * line, int count);
112 static void TransformLine(int const lineno);
113 
114 #ifdef POSITION_DEBUG
115 /****************************************************************************
116  *
117  * Debugging code.  Only works on ANSI-standard terminals.
118  *
119  ****************************************************************************/
120 
121 static void
122 position_check(int expected_y, int expected_x, char *legend)
123 /* check to see if the real cursor position matches the virtual */
124 {
125     char buf[20];
126     char *s;
127     int y, x;
128 
129     if (!_nc_tracing || (expected_y < 0 && expected_x < 0))
130 	return;
131 
132     _nc_flush();
133     memset(buf, '\0', sizeof(buf));
134     putp("\033[6n");		/* only works on ANSI-compatibles */
135     _nc_flush();
136     *(s = buf) = 0;
137     do {
138 	int ask = sizeof(buf) - 1 - (s - buf);
139 	int got = read(0, s, ask);
140 	if (got == 0)
141 	    break;
142 	s += got;
143     } while (strchr(buf, 'R') == 0);
144     _tracef("probe returned %s", _nc_visbuf(buf));
145 
146     /* try to interpret as a position report */
147     if (sscanf(buf, "\033[%d;%dR", &y, &x) != 2) {
148 	_tracef("position probe failed in %s", legend);
149     } else {
150 	if (expected_x < 0)
151 	    expected_x = x - 1;
152 	if (expected_y < 0)
153 	    expected_y = y - 1;
154 	if (y - 1 != expected_y || x - 1 != expected_x) {
155 	    beep();
156 	    tputs(tparm("\033[%d;%dH", expected_y + 1, expected_x + 1), 1, _nc_outch);
157 	    _tracef("position seen (%d, %d) doesn't match expected one (%d, %d) in %s",
158 		    y - 1, x - 1, expected_y, expected_x, legend);
159 	} else {
160 	    _tracef("position matches OK in %s", legend);
161 	}
162     }
163 }
164 #else
165 #define position_check(expected_y, expected_x, legend)	/* nothing */
166 #endif /* POSITION_DEBUG */
167 
168 /****************************************************************************
169  *
170  * Optimized update code
171  *
172  ****************************************************************************/
173 
174 static NCURSES_INLINE void
175 GoTo(int const row, int const col)
176 {
177     TR(TRACE_MOVE, ("GoTo(%d, %d) from (%d, %d)",
178 		    row, col, SP->_cursrow, SP->_curscol));
179 
180     position_check(SP->_cursrow, SP->_curscol, "GoTo");
181 
182     mvcur(SP->_cursrow, SP->_curscol, row, col);
183     position_check(SP->_cursrow, SP->_curscol, "GoTo2");
184 }
185 
186 static NCURSES_INLINE void
187 PutAttrChar(CARG_CH_T ch)
188 {
189     int chlen = 1;
190     NCURSES_CH_T my_ch;
191     PUTC_DATA;
192     NCURSES_CH_T tilde;
193     NCURSES_CH_T attr = CHDEREF(ch);
194 
195     TR(TRACE_CHARPUT, ("PutAttrChar(%s) at (%d, %d)",
196 		       _tracech_t(ch),
197 		       SP->_cursrow, SP->_curscol));
198 #if USE_WIDEC_SUPPORT
199     /*
200      * If this is not a valid character, there is nothing more to do.
201      */
202     if (isWidecExt(CHDEREF(ch))) {
203 	TR(TRACE_CHARPUT, ("...skip"));
204 	return;
205     }
206     /*
207      * Determine the number of character cells which the 'ch' value will use
208      * on the screen.  It should be at least one.
209      */
210     if ((chlen = wcwidth(CharOf(CHDEREF(ch)))) <= 0) {
211 	static const NCURSES_CH_T blank = NewChar(BLANK_TEXT);
212 
213 	/*
214 	 * If the character falls into any of these special cases, do
215 	 * not force the result to a blank:
216 	 *
217 	 * a) it is printable (this works around a bug in wcwidth()).
218 	 * b) use_legacy_coding() has been called to modify the treatment
219 	 *    of codes 128-255.
220 	 * c) the acs_map[] has been initialized to allow codes 0-31
221 	 *    to be rendered.  This supports Linux console's "PC"
222 	 *    characters.  Codes 128-255 are allowed though this is
223 	 *    not checked.
224 	 */
225 	if (is8bits(CharOf(CHDEREF(ch)))
226 	    && (isprint(CharOf(CHDEREF(ch)))
227 		|| (SP->_legacy_coding > 0 && CharOf(CHDEREF(ch)) >= 160)
228 		|| (SP->_legacy_coding > 1 && CharOf(CHDEREF(ch)) >= 128)
229 		|| (AttrOf(attr) & A_ALTCHARSET
230 		    && ((CharOfD(ch) < ACS_LEN
231 			 && SP->_acs_map != 0
232 			 && SP->_acs_map[CharOfD(ch)] != 0)
233 			|| (CharOfD(ch) >= 128))))) {
234 	    ;
235 	} else {
236 	    ch = CHREF(blank);
237 	    TR(TRACE_CHARPUT, ("forced to blank"));
238 	}
239 	chlen = 1;
240     }
241 #endif
242 
243     if ((AttrOf(attr) & A_ALTCHARSET)
244 	&& SP->_acs_map != 0
245 	&& CharOfD(ch) < ACS_LEN) {
246 	my_ch = CHDEREF(ch);	/* work around const param */
247 #if USE_WIDEC_SUPPORT
248 	/*
249 	 * This is crude & ugly, but works most of the time.  It checks if the
250 	 * acs_chars string specified that we have a mapping for this
251 	 * character, and uses the wide-character mapping when we expect the
252 	 * normal one to be broken (by mis-design ;-).
253 	 */
254 	if (SP->_screen_acs_fix
255 	    && SP->_screen_acs_map[CharOf(my_ch)]) {
256 	    RemAttr(attr, A_ALTCHARSET);
257 	    my_ch = _nc_wacs[CharOf(my_ch)];
258 	}
259 #endif
260 	/*
261 	 * If we (still) have alternate character set, it is the normal 8bit
262 	 * flavor.  The _screen_acs_map[] array tells if the character was
263 	 * really in acs_chars, needed because of the way wide/normal line
264 	 * drawing flavors are integrated.
265 	 */
266 	if (AttrOf(attr) & A_ALTCHARSET) {
267 	    int j = CharOfD(ch);
268 	    chtype temp = UChar(SP->_acs_map[j]);
269 
270 	    if (!(SP->_screen_acs_map[j])) {
271 		RemAttr(attr, A_ALTCHARSET);
272 		if (temp == 0)
273 		    temp = ' ';
274 	    }
275 	    if (temp != 0)
276 		SetChar(my_ch, temp, AttrOf(attr));
277 	}
278 	ch = CHREF(my_ch);
279     }
280     if (tilde_glitch && (CharOfD(ch) == L('~'))) {
281 	SetChar(tilde, L('`'), AttrOf(attr));
282 	ch = CHREF(tilde);
283     }
284 
285     UpdateAttrs(attr);
286 #if !USE_WIDEC_SUPPORT
287     /* FIXME - we do this special case for signal handling, should see how to
288      * make it work for wide characters.
289      */
290     if (SP->_outch != 0) {
291 	SP->_outch(UChar(ch));
292     } else
293 #endif
294     {
295 	PUTC(CHDEREF(ch), SP->_ofp);	/* macro's fastest... */
296 	COUNT_OUTCHARS(1);
297     }
298     SP->_curscol += chlen;
299     if (char_padding) {
300 	TPUTS_TRACE("char_padding");
301 	putp(char_padding);
302     }
303 }
304 
305 static bool
306 check_pending(void)
307 /* check for pending input */
308 {
309     bool have_pending = FALSE;
310 
311     /*
312      * Only carry out this check when the flag is zero, otherwise we'll
313      * have the refreshing slow down drastically (or stop) if there's an
314      * unread character available.
315      */
316     if (SP->_fifohold != 0)
317 	return FALSE;
318 
319     if (SP->_checkfd >= 0) {
320 #if USE_FUNC_POLL
321 	struct pollfd fds[1];
322 	fds[0].fd = SP->_checkfd;
323 	fds[0].events = POLLIN;
324 	if (poll(fds, 1, 0) > 0) {
325 	    have_pending = TRUE;
326 	}
327 #elif defined(__BEOS__)
328 	/*
329 	 * BeOS's select() is declared in socket.h, so the configure script does
330 	 * not see it.  That's just as well, since that function works only for
331 	 * sockets.  This (using snooze and ioctl) was distilled from Be's patch
332 	 * for ncurses which uses a separate thread to simulate select().
333 	 *
334 	 * FIXME: the return values from the ioctl aren't very clear if we get
335 	 * interrupted.
336 	 */
337 	int n = 0;
338 	int howmany = ioctl(0, 'ichr', &n);
339 	if (howmany >= 0 && n > 0) {
340 	    have_pending = TRUE;
341 	}
342 #elif HAVE_SELECT
343 	fd_set fdset;
344 	struct timeval ktimeout;
345 
346 	ktimeout.tv_sec =
347 	    ktimeout.tv_usec = 0;
348 
349 	FD_ZERO(&fdset);
350 	FD_SET(SP->_checkfd, &fdset);
351 	if (select(SP->_checkfd + 1, &fdset, NULL, NULL, &ktimeout) != 0) {
352 	    have_pending = TRUE;
353 	}
354 #endif
355     }
356     if (have_pending) {
357 	SP->_fifohold = 5;
358 	_nc_flush();
359     }
360     return FALSE;
361 }
362 
363 /* put char at lower right corner */
364 static void
365 PutCharLR(const ARG_CH_T ch)
366 {
367     if (!auto_right_margin) {
368 	/* we can put the char directly */
369 	PutAttrChar(ch);
370     } else if (enter_am_mode && exit_am_mode) {
371 	/* we can suppress automargin */
372 	TPUTS_TRACE("exit_am_mode");
373 	putp(exit_am_mode);
374 
375 	PutAttrChar(ch);
376 	SP->_curscol--;
377 	position_check(SP->_cursrow, SP->_curscol, "exit_am_mode");
378 
379 	TPUTS_TRACE("enter_am_mode");
380 	putp(enter_am_mode);
381     } else if ((enter_insert_mode && exit_insert_mode)
382 	       || insert_character || parm_ich) {
383 	GoTo(screen_lines - 1, screen_columns - 2);
384 	PutAttrChar(ch);
385 	GoTo(screen_lines - 1, screen_columns - 2);
386 	InsStr(newscr->_line[screen_lines - 1].text + screen_columns - 2, 1);
387     }
388 }
389 
390 /*
391  * Wrap the cursor position, i.e., advance to the beginning of the next line.
392  */
393 static void
394 wrap_cursor(void)
395 {
396     if (eat_newline_glitch) {
397 	/*
398 	 * xenl can manifest two different ways.  The vt100 way is that, when
399 	 * you'd expect the cursor to wrap, it stays hung at the right margin
400 	 * (on top of the character just emitted) and doesn't wrap until the
401 	 * *next* graphic char is emitted.  The c100 way is to ignore LF
402 	 * received just after an am wrap.
403 	 *
404 	 * An aggressive way to handle this would be to emit CR/LF after the
405 	 * char and then assume the wrap is done, you're on the first position
406 	 * of the next line, and the terminal out of its weird state.  Here
407 	 * it's safe to just tell the code that the cursor is in hyperspace and
408 	 * let the next mvcur() call straighten things out.
409 	 */
410 	SP->_curscol = -1;
411 	SP->_cursrow = -1;
412     } else if (auto_right_margin) {
413 	SP->_curscol = 0;
414 	SP->_cursrow++;
415 	/*
416 	 * We've actually moved - but may have to work around problems with
417 	 * video attributes not working.
418 	 */
419 	if (!move_standout_mode && AttrOf(SCREEN_ATTRS(SP))) {
420 	    TR(TRACE_CHARPUT, ("turning off (%#lx) %s before wrapping",
421 			       (unsigned long) AttrOf(SCREEN_ATTRS(SP)),
422 			       _traceattr(AttrOf(SCREEN_ATTRS(SP)))));
423 	    (void) VIDATTR(A_NORMAL, 0);
424 	}
425     } else {
426 	SP->_curscol--;
427     }
428     position_check(SP->_cursrow, SP->_curscol, "wrap_cursor");
429 }
430 
431 static NCURSES_INLINE void
432 PutChar(const ARG_CH_T ch)
433 /* insert character, handling automargin stuff */
434 {
435     if (SP->_cursrow == screen_lines - 1 && SP->_curscol == screen_columns - 1)
436 	PutCharLR(ch);
437     else
438 	PutAttrChar(ch);
439 
440     if (SP->_curscol >= screen_columns)
441 	wrap_cursor();
442 
443     position_check(SP->_cursrow, SP->_curscol, "PutChar");
444 }
445 
446 /*
447  * Check whether the given character can be output by clearing commands.  This
448  * includes test for being a space and not including any 'bad' attributes, such
449  * as A_REVERSE.  All attribute flags which don't affect appearance of a space
450  * or can be output by clearing (A_COLOR in case of bce-terminal) are excluded.
451  */
452 static NCURSES_INLINE bool
453 can_clear_with(ARG_CH_T ch)
454 {
455     if (!back_color_erase && SP->_coloron) {
456 #if NCURSES_EXT_FUNCS
457 	int pair;
458 
459 	if (!SP->_default_color)
460 	    return FALSE;
461 	if (SP->_default_fg != C_MASK || SP->_default_bg != C_MASK)
462 	    return FALSE;
463 	if ((pair = GetPair(CHDEREF(ch))) != 0) {
464 	    short fg, bg;
465 	    pair_content(pair, &fg, &bg);
466 	    if (fg != C_MASK || bg != C_MASK)
467 		return FALSE;
468 	}
469 #else
470 	if (AttrOfD(ch) & A_COLOR)
471 	    return FALSE;
472 #endif
473     }
474     return (ISBLANK(CHDEREF(ch)) &&
475 	    (AttrOfD(ch) & ~(NONBLANK_ATTR | A_COLOR)) == BLANK_ATTR);
476 }
477 
478 /*
479  * Issue a given span of characters from an array.
480  * Must be functionally equivalent to:
481  *	for (i = 0; i < num; i++)
482  *	    PutChar(ntext[i]);
483  * but can leave the cursor positioned at the middle of the interval.
484  *
485  * Returns: 0 - cursor is at the end of interval
486  *	    1 - cursor is somewhere in the middle
487  *
488  * This code is optimized using ech and rep.
489  */
490 static int
491 EmitRange(const NCURSES_CH_T * ntext, int num)
492 {
493     int i;
494 
495     TR(TRACE_CHARPUT, ("EmitRange %d:%s", num, _nc_viscbuf(ntext, num)));
496 
497     if (erase_chars || repeat_char) {
498 	while (num > 0) {
499 	    int runcount;
500 	    NCURSES_CH_T ntext0;
501 
502 	    while (num > 1 && !CharEq(ntext[0], ntext[1])) {
503 		PutChar(CHREF(ntext[0]));
504 		ntext++;
505 		num--;
506 	    }
507 	    ntext0 = ntext[0];
508 	    if (num == 1) {
509 		PutChar(CHREF(ntext0));
510 		return 0;
511 	    }
512 	    runcount = 2;
513 
514 	    while (runcount < num && CharEq(ntext[runcount], ntext0))
515 		runcount++;
516 
517 	    /*
518 	     * The cost expression in the middle isn't exactly right.
519 	     * _cup_ch_cost is an upper bound on the cost for moving to the
520 	     * end of the erased area, but not the cost itself (which we
521 	     * can't compute without emitting the move).  This may result
522 	     * in erase_chars not getting used in some situations for
523 	     * which it would be marginally advantageous.
524 	     */
525 	    if (erase_chars
526 		&& runcount > SP->_ech_cost + SP->_cup_ch_cost
527 		&& can_clear_with(CHREF(ntext0))) {
528 		UpdateAttrs(ntext0);
529 		putp(TPARM_1(erase_chars, runcount));
530 
531 		/*
532 		 * If this is the last part of the given interval,
533 		 * don't bother moving cursor, since it can be the
534 		 * last update on the line.
535 		 */
536 		if (runcount < num) {
537 		    GoTo(SP->_cursrow, SP->_curscol + runcount);
538 		} else {
539 		    return 1;	/* cursor stays in the middle */
540 		}
541 	    } else if (repeat_char && runcount > SP->_rep_cost) {
542 		bool wrap_possible = (SP->_curscol + runcount >= screen_columns);
543 		int rep_count = runcount;
544 
545 		if (wrap_possible)
546 		    rep_count--;
547 
548 		UpdateAttrs(ntext0);
549 		tputs(TPARM_2(repeat_char, CharOf(ntext0), rep_count),
550 		      rep_count, _nc_outch);
551 		SP->_curscol += rep_count;
552 
553 		if (wrap_possible)
554 		    PutChar(CHREF(ntext0));
555 	    } else {
556 		for (i = 0; i < runcount; i++)
557 		    PutChar(CHREF(ntext[i]));
558 	    }
559 	    ntext += runcount;
560 	    num -= runcount;
561 	}
562 	return 0;
563     }
564 
565     for (i = 0; i < num; i++)
566 	PutChar(CHREF(ntext[i]));
567     return 0;
568 }
569 
570 /*
571  * Output the line in the given range [first .. last]
572  *
573  * If there's a run of identical characters that's long enough to justify
574  * cursor movement, use that also.
575  *
576  * Returns: same as EmitRange
577  */
578 static int
579 PutRange(const NCURSES_CH_T * otext,
580 	 const NCURSES_CH_T * ntext,
581 	 int row,
582 	 int first, int last)
583 {
584     int i, j, same;
585 
586     TR(TRACE_CHARPUT, ("PutRange(%p, %p, %d, %d, %d)",
587 		       otext, ntext, row, first, last));
588 
589     if (otext != ntext
590 	&& (last - first + 1) > SP->_inline_cost) {
591 	for (j = first, same = 0; j <= last; j++) {
592 	    if (!same && isWidecExt(otext[j]))
593 		continue;
594 	    if (CharEq(otext[j], ntext[j])) {
595 		same++;
596 	    } else {
597 		if (same > SP->_inline_cost) {
598 		    EmitRange(ntext + first, j - same - first);
599 		    GoTo(row, first = j);
600 		}
601 		same = 0;
602 	    }
603 	}
604 	i = EmitRange(ntext + first, j - same - first);
605 	/*
606 	 * Always return 1 for the next GoTo() after a PutRange() if we found
607 	 * identical characters at end of interval
608 	 */
609 	return (same == 0 ? i : 1);
610     }
611     return EmitRange(ntext + first, last - first + 1);
612 }
613 
614 /* leave unbracketed here so 'indent' works */
615 #define MARK_NOCHANGE(win,row) \
616 		win->_line[row].firstchar = _NOCHANGE; \
617 		win->_line[row].lastchar = _NOCHANGE; \
618 		if_USE_SCROLL_HINTS(win->_line[row].oldindex = row)
619 
620 NCURSES_EXPORT(int)
621 doupdate(void)
622 {
623     int i;
624     int nonempty;
625 #if USE_TRACE_TIMES
626     struct tms before, after;
627 #endif /* USE_TRACE_TIMES */
628 
629     T((T_CALLED("doupdate()")));
630 
631     if (curscr == 0
632 	|| newscr == 0)
633 	returnCode(ERR);
634 
635 #ifdef TRACE
636     if (USE_TRACEF(TRACE_UPDATE)) {
637 	if (curscr->_clear)
638 	    _tracef("curscr is clear");
639 	else
640 	    _tracedump("curscr", curscr);
641 	_tracedump("newscr", newscr);
642 	_nc_unlock_global(tracef);
643     }
644 #endif /* TRACE */
645 
646     _nc_signal_handler(FALSE);
647 
648     if (SP->_fifohold)
649 	SP->_fifohold--;
650 
651 #if USE_SIZECHANGE
652     if (SP->_endwin || _nc_handle_sigwinch(SP)) {
653 	/*
654 	 * This is a transparent extension:  XSI does not address it,
655 	 * and applications need not know that ncurses can do it.
656 	 *
657 	 * Check if the terminal size has changed while curses was off
658 	 * (this can happen in an xterm, for example), and resize the
659 	 * ncurses data structures accordingly.
660 	 */
661 	_nc_update_screensize(SP);
662     }
663 #endif
664 
665     if (SP->_endwin) {
666 
667 	T(("coming back from shell mode"));
668 	reset_prog_mode();
669 
670 	_nc_mvcur_resume();
671 	_nc_screen_resume();
672 	SP->_mouse_resume(SP);
673 
674 	SP->_endwin = FALSE;
675     }
676 #if USE_TRACE_TIMES
677     /* zero the metering machinery */
678     RESET_OUTCHARS();
679     (void) times(&before);
680 #endif /* USE_TRACE_TIMES */
681 
682     /*
683      * This is the support for magic-cookie terminals.  The theory:  we scan
684      * the virtual screen looking for attribute turnons.  Where we find one,
685      * check to make sure it's realizable by seeing if the required number of
686      * un-attributed blanks are present before and after the attributed range;
687      * try to shift the range boundaries over blanks (not changing the screen
688      * display) so this becomes true.  If it is, shift the beginning attribute
689      * change appropriately (the end one, if we've gotten this far, is
690      * guaranteed room for its cookie).  If not, nuke the added attributes out
691      * of the span.
692      */
693 #if USE_XMC_SUPPORT
694     if (magic_cookie_glitch > 0) {
695 	int j, k;
696 	attr_t rattr = A_NORMAL;
697 
698 	for (i = 0; i < screen_lines; i++) {
699 	    for (j = 0; j < screen_columns; j++) {
700 		bool failed = FALSE;
701 		NCURSES_CH_T *thisline = newscr->_line[i].text;
702 		attr_t thisattr = AttrOf(thisline[j]) & SP->_xmc_triggers;
703 		attr_t turnon = thisattr & ~rattr;
704 
705 		/* is an attribute turned on here? */
706 		if (turnon == 0) {
707 		    rattr = thisattr;
708 		    continue;
709 		}
710 
711 		TR(TRACE_ATTRS, ("At (%d, %d): from %s...", i, j, _traceattr(rattr)));
712 		TR(TRACE_ATTRS, ("...to %s", _traceattr(turnon)));
713 
714 		/*
715 		 * If the attribute change location is a blank with a "safe"
716 		 * attribute, undo the attribute turnon.  This may ensure
717 		 * there's enough room to set the attribute before the first
718 		 * non-blank in the run.
719 		 */
720 #define SAFE(a)	(!((a) & SP->_xmc_triggers))
721 		if (ISBLANK(thisline[j]) && SAFE(turnon)) {
722 		    RemAttr(thisline[j], turnon);
723 		    continue;
724 		}
725 
726 		/* check that there's enough room at start of span */
727 		for (k = 1; k <= magic_cookie_glitch; k++) {
728 		    if (j - k < 0
729 			|| !ISBLANK(thisline[j - k])
730 			|| !SAFE(AttrOf(thisline[j - k]))) {
731 			failed = TRUE;
732 			TR(TRACE_ATTRS, ("No room at start in %d,%d%s%s",
733 					 i, j - k,
734 					 (ISBLANK(thisline[j - k])
735 					  ? ""
736 					  : ":nonblank"),
737 					 (SAFE(AttrOf(thisline[j - k]))
738 					  ? ""
739 					  : ":unsafe")));
740 			break;
741 		    }
742 		}
743 		if (!failed) {
744 		    bool end_onscreen = FALSE;
745 		    int m, n = j;
746 
747 		    /* find end of span, if it's onscreen */
748 		    for (m = i; m < screen_lines; m++) {
749 			for (; n < screen_columns; n++) {
750 			    attr_t testattr = AttrOf(newscr->_line[m].text[n]);
751 			    if ((testattr & SP->_xmc_triggers) == rattr) {
752 				end_onscreen = TRUE;
753 				TR(TRACE_ATTRS,
754 				   ("Range attributed with %s ends at (%d, %d)",
755 				    _traceattr(turnon), m, n));
756 				goto foundit;
757 			    }
758 			}
759 			n = 0;
760 		    }
761 		    TR(TRACE_ATTRS,
762 		       ("Range attributed with %s ends offscreen",
763 			_traceattr(turnon)));
764 		  foundit:;
765 
766 		    if (end_onscreen) {
767 			NCURSES_CH_T *lastline = newscr->_line[m].text;
768 
769 			/*
770 			 * If there are safely-attributed blanks at the end of
771 			 * the range, shorten the range.  This will help ensure
772 			 * that there is enough room at end of span.
773 			 */
774 			while (n >= 0
775 			       && ISBLANK(lastline[n])
776 			       && SAFE(AttrOf(lastline[n]))) {
777 			    RemAttr(lastline[n--], turnon);
778 			}
779 
780 			/* check that there's enough room at end of span */
781 			for (k = 1; k <= magic_cookie_glitch; k++) {
782 			    if (n + k >= screen_columns
783 				|| !ISBLANK(lastline[n + k])
784 				|| !SAFE(AttrOf(lastline[n + k]))) {
785 				failed = TRUE;
786 				TR(TRACE_ATTRS,
787 				   ("No room at end in %d,%d%s%s",
788 				    i, j - k,
789 				    (ISBLANK(lastline[n + k])
790 				     ? ""
791 				     : ":nonblank"),
792 				    (SAFE(AttrOf(lastline[n + k]))
793 				     ? ""
794 				     : ":unsafe")));
795 				break;
796 			    }
797 			}
798 		    }
799 		}
800 
801 		if (failed) {
802 		    int p, q = j;
803 
804 		    TR(TRACE_ATTRS,
805 		       ("Clearing %s beginning at (%d, %d)",
806 			_traceattr(turnon), i, j));
807 
808 		    /* turn off new attributes over span */
809 		    for (p = i; p < screen_lines; p++) {
810 			for (; q < screen_columns; q++) {
811 			    attr_t testattr = AttrOf(newscr->_line[p].text[q]);
812 			    if ((testattr & SP->_xmc_triggers) == rattr)
813 				goto foundend;
814 			    RemAttr(newscr->_line[p].text[q], turnon);
815 			}
816 			q = 0;
817 		    }
818 		  foundend:;
819 		} else {
820 		    TR(TRACE_ATTRS,
821 		       ("Cookie space for %s found before (%d, %d)",
822 			_traceattr(turnon), i, j));
823 
824 		    /*
825 		     * Back up the start of range so there's room for cookies
826 		     * before the first nonblank character.
827 		     */
828 		    for (k = 1; k <= magic_cookie_glitch; k++)
829 			AddAttr(thisline[j - k], turnon);
830 		}
831 
832 		rattr = thisattr;
833 	    }
834 	}
835 
836 #ifdef TRACE
837 	/* show altered highlights after magic-cookie check */
838 	if (USE_TRACEF(TRACE_UPDATE)) {
839 	    _tracef("After magic-cookie check...");
840 	    _tracedump("newscr", newscr);
841 	    _nc_unlock_global(tracef);
842 	}
843 #endif /* TRACE */
844     }
845 #endif /* USE_XMC_SUPPORT */
846 
847     nonempty = 0;
848     if (curscr->_clear || newscr->_clear) {	/* force refresh ? */
849 	ClrUpdate();
850 	curscr->_clear = FALSE;	/* reset flag */
851 	newscr->_clear = FALSE;	/* reset flag */
852     } else {
853 	int changedlines = CHECK_INTERVAL;
854 
855 	if (check_pending())
856 	    goto cleanup;
857 
858 	nonempty = min(screen_lines, newscr->_maxy + 1);
859 
860 	if (SP->_scrolling) {
861 	    _nc_scroll_optimize();
862 	}
863 
864 	nonempty = ClrBottom(nonempty);
865 
866 	TR(TRACE_UPDATE, ("Transforming lines, nonempty %d", nonempty));
867 	for (i = 0; i < nonempty; i++) {
868 	    /*
869 	     * Here is our line-breakout optimization.
870 	     */
871 	    if (changedlines == CHECK_INTERVAL) {
872 		if (check_pending())
873 		    goto cleanup;
874 		changedlines = 0;
875 	    }
876 
877 	    /*
878 	     * newscr->line[i].firstchar is normally set
879 	     * by wnoutrefresh.  curscr->line[i].firstchar
880 	     * is normally set by _nc_scroll_window in the
881 	     * vertical-movement optimization code,
882 	     */
883 	    if (newscr->_line[i].firstchar != _NOCHANGE
884 		|| curscr->_line[i].firstchar != _NOCHANGE) {
885 		TransformLine(i);
886 		changedlines++;
887 	    }
888 
889 	    /* mark line changed successfully */
890 	    if (i <= newscr->_maxy) {
891 		MARK_NOCHANGE(newscr, i);
892 	    }
893 	    if (i <= curscr->_maxy) {
894 		MARK_NOCHANGE(curscr, i);
895 	    }
896 	}
897     }
898 
899     /* put everything back in sync */
900     for (i = nonempty; i <= newscr->_maxy; i++) {
901 	MARK_NOCHANGE(newscr, i);
902     }
903     for (i = nonempty; i <= curscr->_maxy; i++) {
904 	MARK_NOCHANGE(curscr, i);
905     }
906 
907     if (!newscr->_leaveok) {
908 	curscr->_curx = newscr->_curx;
909 	curscr->_cury = newscr->_cury;
910 
911 	GoTo(curscr->_cury, curscr->_curx);
912     }
913 
914   cleanup:
915     /*
916      * We would like to keep the physical screen in normal mode in case we get
917      * other processes writing to the screen.  This goal cannot be met for
918      * magic cookies since it interferes with attributes that may propagate
919      * past the current position.
920      */
921 #if USE_XMC_SUPPORT
922     if (magic_cookie_glitch != 0)
923 #endif
924 	UpdateAttrs(normal);
925 
926     _nc_flush();
927     WINDOW_ATTRS(curscr) = WINDOW_ATTRS(newscr);
928 
929 #if USE_TRACE_TIMES
930     (void) times(&after);
931     TR(TRACE_TIMES,
932        ("Update cost: %ld chars, %ld clocks system time, %ld clocks user time",
933 	_nc_outchars,
934 	(long) (after.tms_stime - before.tms_stime),
935 	(long) (after.tms_utime - before.tms_utime)));
936 #endif /* USE_TRACE_TIMES */
937 
938     _nc_signal_handler(TRUE);
939 
940     returnCode(OK);
941 }
942 
943 /*
944  *	ClrBlank(win)
945  *
946  *	Returns the attributed character that corresponds to the "cleared"
947  *	screen.  If the terminal has the back-color-erase feature, this will be
948  *	colored according to the wbkgd() call.
949  *
950  *	We treat 'curscr' specially because it isn't supposed to be set directly
951  *	in the wbkgd() call.  Assume 'stdscr' for this case.
952  */
953 #define BCE_ATTRS (A_NORMAL|A_COLOR)
954 #define BCE_BKGD(win) (((win) == curscr ? stdscr : (win))->_nc_bkgd)
955 
956 static NCURSES_INLINE NCURSES_CH_T
957 ClrBlank(WINDOW *win)
958 {
959     NCURSES_CH_T blank = blankchar;
960     if (back_color_erase)
961 	AddAttr(blank, (AttrOf(BCE_BKGD(win)) & BCE_ATTRS));
962     return blank;
963 }
964 
965 /*
966 **	ClrUpdate()
967 **
968 **	Update by clearing and redrawing the entire screen.
969 **
970 */
971 
972 static void
973 ClrUpdate(void)
974 {
975     int i;
976     NCURSES_CH_T blank = ClrBlank(stdscr);
977     int nonempty = min(screen_lines, newscr->_maxy + 1);
978 
979     TR(TRACE_UPDATE, (T_CALLED("ClrUpdate")));
980 
981     ClearScreen(blank);
982 
983     TR(TRACE_UPDATE, ("updating screen from scratch"));
984 
985     nonempty = ClrBottom(nonempty);
986 
987     for (i = 0; i < nonempty; i++)
988 	TransformLine(i);
989 
990     TR(TRACE_UPDATE, (T_RETURN("")));
991 }
992 
993 /*
994 **	ClrToEOL(blank)
995 **
996 **	Clear to end of current line, starting at the cursor position
997 */
998 
999 static void
1000 ClrToEOL(NCURSES_CH_T blank, bool needclear)
1001 {
1002     int j;
1003 
1004     if (curscr != 0
1005 	&& SP->_cursrow >= 0) {
1006 	for (j = SP->_curscol; j < screen_columns; j++) {
1007 	    if (j >= 0) {
1008 		NCURSES_CH_T *cp = &(curscr->_line[SP->_cursrow].text[j]);
1009 
1010 		if (!CharEq(*cp, blank)) {
1011 		    *cp = blank;
1012 		    needclear = TRUE;
1013 		}
1014 	    }
1015 	}
1016     } else {
1017 	needclear = TRUE;
1018     }
1019 
1020     if (needclear) {
1021 	UpdateAttrs(blank);
1022 	TPUTS_TRACE("clr_eol");
1023 	if (clr_eol && SP->_el_cost <= (screen_columns - SP->_curscol)) {
1024 	    putp(clr_eol);
1025 	} else {
1026 	    int count = (screen_columns - SP->_curscol);
1027 	    while (count-- > 0)
1028 		PutChar(CHREF(blank));
1029 	}
1030     }
1031 }
1032 
1033 /*
1034 **	ClrToEOS(blank)
1035 **
1036 **	Clear to end of screen, starting at the cursor position
1037 */
1038 
1039 static void
1040 ClrToEOS(NCURSES_CH_T blank)
1041 {
1042     int row, col;
1043 
1044     row = SP->_cursrow;
1045     col = SP->_curscol;
1046 
1047     UpdateAttrs(blank);
1048     TPUTS_TRACE("clr_eos");
1049     tputs(clr_eos, screen_lines - row, _nc_outch);
1050 
1051     while (col < screen_columns)
1052 	curscr->_line[row].text[col++] = blank;
1053 
1054     for (row++; row < screen_lines; row++) {
1055 	for (col = 0; col < screen_columns; col++)
1056 	    curscr->_line[row].text[col] = blank;
1057     }
1058 }
1059 
1060 /*
1061  *	ClrBottom(total)
1062  *
1063  *	Test if clearing the end of the screen would satisfy part of the
1064  *	screen-update.  Do this by scanning backwards through the lines in the
1065  *	screen, checking if each is blank, and one or more are changed.
1066  */
1067 static int
1068 ClrBottom(int total)
1069 {
1070     int row;
1071     int col;
1072     int top = total;
1073     int last = min(screen_columns, newscr->_maxx + 1);
1074     NCURSES_CH_T blank = newscr->_line[total - 1].text[last - 1];
1075     bool ok;
1076 
1077     if (clr_eos && can_clear_with(CHREF(blank))) {
1078 
1079 	for (row = total - 1; row >= 0; row--) {
1080 	    for (col = 0, ok = TRUE; ok && col < last; col++) {
1081 		ok = (CharEq(newscr->_line[row].text[col], blank));
1082 	    }
1083 	    if (!ok)
1084 		break;
1085 
1086 	    for (col = 0; ok && col < last; col++) {
1087 		ok = (CharEq(curscr->_line[row].text[col], blank));
1088 	    }
1089 	    if (!ok)
1090 		top = row;
1091 	}
1092 
1093 	/* don't use clr_eos for just one line if clr_eol available */
1094 	if (top < total) {
1095 	    GoTo(top, 0);
1096 	    ClrToEOS(blank);
1097 	    if (SP->oldhash && SP->newhash) {
1098 		for (row = top; row < screen_lines; row++)
1099 		    SP->oldhash[row] = SP->newhash[row];
1100 	    }
1101 	}
1102     }
1103     return top;
1104 }
1105 
1106 #if USE_XMC_SUPPORT
1107 #if USE_WIDEC_SUPPORT
1108 #define check_xmc_transition(a, b) \
1109     ((((a)->attr ^ (b)->attr) & ~((a)->attr) & SP->_xmc_triggers) != 0)
1110 #define xmc_turn_on(a,b) check_xmc_transition(&(a), &(b))
1111 #else
1112 #define xmc_turn_on(a,b) ((((a)^(b)) & ~(a) & SP->_xmc_triggers) != 0)
1113 #endif
1114 
1115 #define xmc_new(r,c) newscr->_line[r].text[c]
1116 #define xmc_turn_off(a,b) xmc_turn_on(b,a)
1117 #endif /* USE_XMC_SUPPORT */
1118 
1119 /*
1120 **	TransformLine(lineno)
1121 **
1122 **	Transform the given line in curscr to the one in newscr, using
1123 **	Insert/Delete Character if _nc_idcok && has_ic().
1124 **
1125 **		firstChar = position of first different character in line
1126 **		oLastChar = position of last different character in old line
1127 **		nLastChar = position of last different character in new line
1128 **
1129 **		move to firstChar
1130 **		overwrite chars up to min(oLastChar, nLastChar)
1131 **		if oLastChar < nLastChar
1132 **			insert newLine[oLastChar+1..nLastChar]
1133 **		else
1134 **			delete oLastChar - nLastChar spaces
1135 */
1136 
1137 static void
1138 TransformLine(int const lineno)
1139 {
1140     int firstChar, oLastChar, nLastChar;
1141     NCURSES_CH_T *newLine = newscr->_line[lineno].text;
1142     NCURSES_CH_T *oldLine = curscr->_line[lineno].text;
1143     int n;
1144     bool attrchanged = FALSE;
1145 
1146     TR(TRACE_UPDATE, (T_CALLED("TransformLine(%d)"), lineno));
1147 
1148     /* copy new hash value to old one */
1149     if (SP->oldhash && SP->newhash)
1150 	SP->oldhash[lineno] = SP->newhash[lineno];
1151 
1152     /*
1153      * If we have colors, there is the possibility of having two color pairs
1154      * that display as the same colors.  For instance, Lynx does this.  Check
1155      * for this case, and update the old line with the new line's colors when
1156      * they are equivalent.
1157      */
1158     if (SP->_coloron) {
1159 	int oldPair;
1160 	int newPair;
1161 
1162 	for (n = 0; n < screen_columns; n++) {
1163 	    if (!CharEq(newLine[n], oldLine[n])) {
1164 		oldPair = GetPair(oldLine[n]);
1165 		newPair = GetPair(newLine[n]);
1166 		if (oldPair != newPair
1167 		    && unColor(oldLine[n]) == unColor(newLine[n])) {
1168 		    if (oldPair < COLOR_PAIRS
1169 			&& newPair < COLOR_PAIRS
1170 			&& SP->_color_pairs[oldPair] == SP->_color_pairs[newPair]) {
1171 			SetPair(oldLine[n], GetPair(newLine[n]));
1172 		    }
1173 		}
1174 	    }
1175 	}
1176     }
1177 
1178     if (ceol_standout_glitch && clr_eol) {
1179 	firstChar = 0;
1180 	while (firstChar < screen_columns) {
1181 	    if (!SameAttrOf(newLine[firstChar], oldLine[firstChar])) {
1182 		attrchanged = TRUE;
1183 		break;
1184 	    }
1185 	    firstChar++;
1186 	}
1187     }
1188 
1189     firstChar = 0;
1190 
1191     if (attrchanged) {		/* we may have to disregard the whole line */
1192 	GoTo(lineno, firstChar);
1193 	ClrToEOL(ClrBlank(curscr), FALSE);
1194 	PutRange(oldLine, newLine, lineno, 0, (screen_columns - 1));
1195 #if USE_XMC_SUPPORT
1196 
1197 	/*
1198 	 * This is a very simple loop to paint characters which may have the
1199 	 * magic cookie glitch embedded.  It doesn't know much about video
1200 	 * attributes which are continued from one line to the next.  It
1201 	 * assumes that we have filtered out requests for attribute changes
1202 	 * that do not get mapped to blank positions.
1203 	 *
1204 	 * FIXME: we are not keeping track of where we put the cookies, so this
1205 	 * will work properly only once, since we may overwrite a cookie in a
1206 	 * following operation.
1207 	 */
1208     } else if (magic_cookie_glitch > 0) {
1209 	GoTo(lineno, firstChar);
1210 	for (n = 0; n < screen_columns; n++) {
1211 	    int m = n + magic_cookie_glitch;
1212 
1213 	    /* check for turn-on:
1214 	     * If we are writing an attributed blank, where the
1215 	     * previous cell is not attributed.
1216 	     */
1217 	    if (ISBLANK(newLine[n])
1218 		&& ((n > 0
1219 		     && xmc_turn_on(newLine[n - 1], newLine[n]))
1220 		    || (n == 0
1221 			&& lineno > 0
1222 			&& xmc_turn_on(xmc_new(lineno - 1, screen_columns - 1),
1223 				       newLine[n])))) {
1224 		n = m;
1225 	    }
1226 
1227 	    PutChar(CHREF(newLine[n]));
1228 
1229 	    /* check for turn-off:
1230 	     * If we are writing an attributed non-blank, where the
1231 	     * next cell is blank, and not attributed.
1232 	     */
1233 	    if (!ISBLANK(newLine[n])
1234 		&& ((n + 1 < screen_columns
1235 		     && xmc_turn_off(newLine[n], newLine[n + 1]))
1236 		    || (n + 1 >= screen_columns
1237 			&& lineno + 1 < screen_lines
1238 			&& xmc_turn_off(newLine[n], xmc_new(lineno + 1, 0))))) {
1239 		n = m;
1240 	    }
1241 
1242 	}
1243 #endif
1244     } else {
1245 	NCURSES_CH_T blank;
1246 
1247 	/* it may be cheap to clear leading whitespace with clr_bol */
1248 	blank = newLine[0];
1249 	if (clr_bol && can_clear_with(CHREF(blank))) {
1250 	    int oFirstChar, nFirstChar;
1251 
1252 	    for (oFirstChar = 0; oFirstChar < screen_columns; oFirstChar++)
1253 		if (!CharEq(oldLine[oFirstChar], blank))
1254 		    break;
1255 	    for (nFirstChar = 0; nFirstChar < screen_columns; nFirstChar++)
1256 		if (!CharEq(newLine[nFirstChar], blank))
1257 		    break;
1258 
1259 	    if (nFirstChar == oFirstChar) {
1260 		firstChar = nFirstChar;
1261 		/* find the first differing character */
1262 		while (firstChar < screen_columns
1263 		       && CharEq(newLine[firstChar], oldLine[firstChar]))
1264 		    firstChar++;
1265 	    } else if (oFirstChar > nFirstChar) {
1266 		firstChar = nFirstChar;
1267 	    } else {		/* oFirstChar < nFirstChar */
1268 		firstChar = oFirstChar;
1269 		if (SP->_el1_cost < nFirstChar - oFirstChar) {
1270 		    if (nFirstChar >= screen_columns
1271 			&& SP->_el_cost <= SP->_el1_cost) {
1272 			GoTo(lineno, 0);
1273 			UpdateAttrs(blank);
1274 			TPUTS_TRACE("clr_eol");
1275 			putp(clr_eol);
1276 		    } else {
1277 			GoTo(lineno, nFirstChar - 1);
1278 			UpdateAttrs(blank);
1279 			TPUTS_TRACE("clr_bol");
1280 			putp(clr_bol);
1281 		    }
1282 
1283 		    while (firstChar < nFirstChar)
1284 			oldLine[firstChar++] = blank;
1285 		}
1286 	    }
1287 	} else {
1288 	    /* find the first differing character */
1289 	    while (firstChar < screen_columns
1290 		   && CharEq(newLine[firstChar], oldLine[firstChar]))
1291 		firstChar++;
1292 	}
1293 	/* if there wasn't one, we're done */
1294 	if (firstChar >= screen_columns) {
1295 	    TR(TRACE_UPDATE, (T_RETURN("")));
1296 	    return;
1297 	}
1298 
1299 	blank = newLine[screen_columns - 1];
1300 
1301 	if (!can_clear_with(CHREF(blank))) {
1302 	    /* find the last differing character */
1303 	    nLastChar = screen_columns - 1;
1304 
1305 	    while (nLastChar > firstChar
1306 		   && CharEq(newLine[nLastChar], oldLine[nLastChar]))
1307 		nLastChar--;
1308 
1309 	    if (nLastChar >= firstChar) {
1310 		GoTo(lineno, firstChar);
1311 		PutRange(oldLine, newLine, lineno, firstChar, nLastChar);
1312 		memcpy(oldLine + firstChar,
1313 		       newLine + firstChar,
1314 		       (nLastChar - firstChar + 1) * sizeof(NCURSES_CH_T));
1315 	    }
1316 	    TR(TRACE_UPDATE, (T_RETURN("")));
1317 	    return;
1318 	}
1319 
1320 	/* find last non-blank character on old line */
1321 	oLastChar = screen_columns - 1;
1322 	while (oLastChar > firstChar && CharEq(oldLine[oLastChar], blank))
1323 	    oLastChar--;
1324 
1325 	/* find last non-blank character on new line */
1326 	nLastChar = screen_columns - 1;
1327 	while (nLastChar > firstChar && CharEq(newLine[nLastChar], blank))
1328 	    nLastChar--;
1329 
1330 	if ((nLastChar == firstChar)
1331 	    && (SP->_el_cost < (oLastChar - nLastChar))) {
1332 	    GoTo(lineno, firstChar);
1333 	    if (!CharEq(newLine[firstChar], blank))
1334 		PutChar(CHREF(newLine[firstChar]));
1335 	    ClrToEOL(blank, FALSE);
1336 	} else if ((nLastChar != oLastChar)
1337 		   && (!CharEq(newLine[nLastChar], oldLine[oLastChar])
1338 		       || !(_nc_idcok && has_ic()))) {
1339 	    GoTo(lineno, firstChar);
1340 	    if ((oLastChar - nLastChar) > SP->_el_cost) {
1341 		if (PutRange(oldLine, newLine, lineno, firstChar, nLastChar))
1342 		    GoTo(lineno, nLastChar + 1);
1343 		ClrToEOL(blank, FALSE);
1344 	    } else {
1345 		n = max(nLastChar, oLastChar);
1346 		PutRange(oldLine, newLine, lineno, firstChar, n);
1347 	    }
1348 	} else {
1349 	    int nLastNonblank = nLastChar;
1350 	    int oLastNonblank = oLastChar;
1351 
1352 	    /* find the last characters that really differ */
1353 	    /* can be -1 if no characters differ */
1354 	    while (CharEq(newLine[nLastChar], oldLine[oLastChar])) {
1355 		/* don't split a wide char */
1356 		if (isWidecExt(newLine[nLastChar]) &&
1357 		    !CharEq(newLine[nLastChar - 1], oldLine[oLastChar - 1]))
1358 		    break;
1359 		nLastChar--;
1360 		oLastChar--;
1361 		if (nLastChar == -1 || oLastChar == -1)
1362 		    break;
1363 	    }
1364 
1365 	    n = min(oLastChar, nLastChar);
1366 	    if (n >= firstChar) {
1367 		GoTo(lineno, firstChar);
1368 		PutRange(oldLine, newLine, lineno, firstChar, n);
1369 	    }
1370 
1371 	    if (oLastChar < nLastChar) {
1372 		int m = max(nLastNonblank, oLastNonblank);
1373 #if USE_WIDEC_SUPPORT
1374 		while (isWidecExt(newLine[n + 1]) && n) {
1375 		    --n;
1376 		    --oLastChar;
1377 		}
1378 #endif
1379 		GoTo(lineno, n + 1);
1380 		if ((nLastChar < nLastNonblank)
1381 		    || InsCharCost(nLastChar - oLastChar) > (m - n)) {
1382 		    PutRange(oldLine, newLine, lineno, n + 1, m);
1383 		} else {
1384 		    InsStr(&newLine[n + 1], nLastChar - oLastChar);
1385 		}
1386 	    } else if (oLastChar > nLastChar) {
1387 		GoTo(lineno, n + 1);
1388 		if (DelCharCost(oLastChar - nLastChar)
1389 		    > SP->_el_cost + nLastNonblank - (n + 1)) {
1390 		    if (PutRange(oldLine, newLine, lineno,
1391 				 n + 1, nLastNonblank))
1392 			GoTo(lineno, nLastNonblank + 1);
1393 		    ClrToEOL(blank, FALSE);
1394 		} else {
1395 		    /*
1396 		     * The delete-char sequence will
1397 		     * effectively shift in blanks from the
1398 		     * right margin of the screen.  Ensure
1399 		     * that they are the right color by
1400 		     * setting the video attributes from
1401 		     * the last character on the row.
1402 		     */
1403 		    UpdateAttrs(blank);
1404 		    DelChar(oLastChar - nLastChar);
1405 		}
1406 	    }
1407 	}
1408     }
1409 
1410     /* update the code's internal representation */
1411     if (screen_columns > firstChar)
1412 	memcpy(oldLine + firstChar,
1413 	       newLine + firstChar,
1414 	       (screen_columns - firstChar) * sizeof(NCURSES_CH_T));
1415     TR(TRACE_UPDATE, (T_RETURN("")));
1416     return;
1417 }
1418 
1419 /*
1420 **	ClearScreen(blank)
1421 **
1422 **	Clear the physical screen and put cursor at home
1423 **
1424 */
1425 
1426 static void
1427 ClearScreen(NCURSES_CH_T blank)
1428 {
1429     int i, j;
1430     bool fast_clear = (clear_screen || clr_eos || clr_eol);
1431 
1432     TR(TRACE_UPDATE, ("ClearScreen() called"));
1433 
1434 #if NCURSES_EXT_FUNCS
1435     if (SP->_coloron
1436 	&& !SP->_default_color) {
1437 	_nc_do_color(GET_SCREEN_PAIR(SP), 0, FALSE, _nc_outch);
1438 	if (!back_color_erase) {
1439 	    fast_clear = FALSE;
1440 	}
1441     }
1442 #endif
1443 
1444     if (fast_clear) {
1445 	if (clear_screen) {
1446 	    UpdateAttrs(blank);
1447 	    TPUTS_TRACE("clear_screen");
1448 	    putp(clear_screen);
1449 	    SP->_cursrow = SP->_curscol = 0;
1450 	    position_check(SP->_cursrow, SP->_curscol, "ClearScreen");
1451 	} else if (clr_eos) {
1452 	    SP->_cursrow = SP->_curscol = -1;
1453 	    GoTo(0, 0);
1454 
1455 	    UpdateAttrs(blank);
1456 	    TPUTS_TRACE("clr_eos");
1457 	    tputs(clr_eos, screen_lines, _nc_outch);
1458 	} else if (clr_eol) {
1459 	    SP->_cursrow = SP->_curscol = -1;
1460 
1461 	    UpdateAttrs(blank);
1462 	    for (i = 0; i < screen_lines; i++) {
1463 		GoTo(i, 0);
1464 		TPUTS_TRACE("clr_eol");
1465 		putp(clr_eol);
1466 	    }
1467 	    GoTo(0, 0);
1468 	}
1469     } else {
1470 	UpdateAttrs(blank);
1471 	for (i = 0; i < screen_lines; i++) {
1472 	    GoTo(i, 0);
1473 	    for (j = 0; j < screen_columns; j++)
1474 		PutChar(CHREF(blank));
1475 	}
1476 	GoTo(0, 0);
1477     }
1478 
1479     for (i = 0; i < screen_lines; i++) {
1480 	for (j = 0; j < screen_columns; j++)
1481 	    curscr->_line[i].text[j] = blank;
1482     }
1483 
1484     TR(TRACE_UPDATE, ("screen cleared"));
1485 }
1486 
1487 /*
1488 **	InsStr(line, count)
1489 **
1490 **	Insert the count characters pointed to by line.
1491 **
1492 */
1493 
1494 static void
1495 InsStr(NCURSES_CH_T * line, int count)
1496 {
1497     TR(TRACE_UPDATE, ("InsStr(%p,%d) called", line, count));
1498 
1499     /* Prefer parm_ich as it has the smallest cost - no need to shift
1500      * the whole line on each character. */
1501     /* The order must match that of InsCharCost. */
1502     if (parm_ich) {
1503 	TPUTS_TRACE("parm_ich");
1504 	tputs(TPARM_1(parm_ich, count), count, _nc_outch);
1505 	while (count) {
1506 	    PutAttrChar(CHREF(*line));
1507 	    line++;
1508 	    count--;
1509 	}
1510     } else if (enter_insert_mode && exit_insert_mode) {
1511 	TPUTS_TRACE("enter_insert_mode");
1512 	putp(enter_insert_mode);
1513 	while (count) {
1514 	    PutAttrChar(CHREF(*line));
1515 	    if (insert_padding) {
1516 		TPUTS_TRACE("insert_padding");
1517 		putp(insert_padding);
1518 	    }
1519 	    line++;
1520 	    count--;
1521 	}
1522 	TPUTS_TRACE("exit_insert_mode");
1523 	putp(exit_insert_mode);
1524     } else {
1525 	while (count) {
1526 	    TPUTS_TRACE("insert_character");
1527 	    putp(insert_character);
1528 	    PutAttrChar(CHREF(*line));
1529 	    if (insert_padding) {
1530 		TPUTS_TRACE("insert_padding");
1531 		putp(insert_padding);
1532 	    }
1533 	    line++;
1534 	    count--;
1535 	}
1536     }
1537     position_check(SP->_cursrow, SP->_curscol, "InsStr");
1538 }
1539 
1540 /*
1541 **	DelChar(count)
1542 **
1543 **	Delete count characters at current position
1544 **
1545 */
1546 
1547 static void
1548 DelChar(int count)
1549 {
1550     int n;
1551 
1552     TR(TRACE_UPDATE, ("DelChar(%d) called, position = (%ld,%ld)",
1553 		      count,
1554 		      (long) newscr->_cury,
1555 		      (long) newscr->_curx));
1556 
1557     if (parm_dch) {
1558 	TPUTS_TRACE("parm_dch");
1559 	tputs(TPARM_1(parm_dch, count), count, _nc_outch);
1560     } else {
1561 	for (n = 0; n < count; n++) {
1562 	    TPUTS_TRACE("delete_character");
1563 	    putp(delete_character);
1564 	}
1565     }
1566 }
1567 
1568 /*
1569  * Physical-scrolling support
1570  *
1571  * This code was adapted from Keith Bostic's hardware scrolling
1572  * support for 4.4BSD curses.  I (esr) translated it to use terminfo
1573  * capabilities, narrowed the call interface slightly, and cleaned
1574  * up some convoluted tests.  I also added support for the memory_above
1575  * memory_below, and non_dest_scroll_region capabilities.
1576  *
1577  * For this code to work, we must have either
1578  * change_scroll_region and scroll forward/reverse commands, or
1579  * insert and delete line capabilities.
1580  * When the scrolling region has been set, the cursor has to
1581  * be at the last line of the region to make the scroll up
1582  * happen, or on the first line of region to scroll down.
1583  *
1584  * This code makes one aesthetic decision in the opposite way from
1585  * BSD curses.  BSD curses preferred pairs of il/dl operations
1586  * over scrolls, allegedly because il/dl looked faster.  We, on
1587  * the other hand, prefer scrolls because (a) they're just as fast
1588  * on many terminals and (b) using them avoids bouncing an
1589  * unchanged bottom section of the screen up and down, which is
1590  * visually nasty.
1591  *
1592  * (lav): added more cases, used dl/il when bot==maxy and in csr case.
1593  *
1594  * I used assumption that capabilities il/il1/dl/dl1 work inside
1595  * changed scroll region not shifting screen contents outside of it.
1596  * If there are any terminals behaving different way, it would be
1597  * necessary to add some conditions to scroll_csr_forward/backward.
1598  */
1599 
1600 /* Try to scroll up assuming given csr (miny, maxy). Returns ERR on failure */
1601 static int
1602 scroll_csr_forward(int n, int top, int bot, int miny, int maxy, NCURSES_CH_T blank)
1603 {
1604     int i;
1605 
1606     if (n == 1 && scroll_forward && top == miny && bot == maxy) {
1607 	GoTo(bot, 0);
1608 	UpdateAttrs(blank);
1609 	TPUTS_TRACE("scroll_forward");
1610 	putp(scroll_forward);
1611     } else if (n == 1 && delete_line && bot == maxy) {
1612 	GoTo(top, 0);
1613 	UpdateAttrs(blank);
1614 	TPUTS_TRACE("delete_line");
1615 	putp(delete_line);
1616     } else if (parm_index && top == miny && bot == maxy) {
1617 	GoTo(bot, 0);
1618 	UpdateAttrs(blank);
1619 	TPUTS_TRACE("parm_index");
1620 	tputs(TPARM_2(parm_index, n, 0), n, _nc_outch);
1621     } else if (parm_delete_line && bot == maxy) {
1622 	GoTo(top, 0);
1623 	UpdateAttrs(blank);
1624 	TPUTS_TRACE("parm_delete_line");
1625 	tputs(TPARM_2(parm_delete_line, n, 0), n, _nc_outch);
1626     } else if (scroll_forward && top == miny && bot == maxy) {
1627 	GoTo(bot, 0);
1628 	UpdateAttrs(blank);
1629 	for (i = 0; i < n; i++) {
1630 	    TPUTS_TRACE("scroll_forward");
1631 	    putp(scroll_forward);
1632 	}
1633     } else if (delete_line && bot == maxy) {
1634 	GoTo(top, 0);
1635 	UpdateAttrs(blank);
1636 	for (i = 0; i < n; i++) {
1637 	    TPUTS_TRACE("delete_line");
1638 	    putp(delete_line);
1639 	}
1640     } else
1641 	return ERR;
1642 
1643 #if NCURSES_EXT_FUNCS
1644     if (FILL_BCE()) {
1645 	int j;
1646 	for (i = 0; i < n; i++) {
1647 	    GoTo(bot - i, 0);
1648 	    for (j = 0; j < screen_columns; j++)
1649 		PutChar(CHREF(blank));
1650 	}
1651     }
1652 #endif
1653     return OK;
1654 }
1655 
1656 /* Try to scroll down assuming given csr (miny, maxy). Returns ERR on failure */
1657 /* n > 0 */
1658 static int
1659 scroll_csr_backward(int n, int top, int bot, int miny, int maxy,
1660 		    NCURSES_CH_T blank)
1661 {
1662     int i;
1663 
1664     if (n == 1 && scroll_reverse && top == miny && bot == maxy) {
1665 	GoTo(top, 0);
1666 	UpdateAttrs(blank);
1667 	TPUTS_TRACE("scroll_reverse");
1668 	putp(scroll_reverse);
1669     } else if (n == 1 && insert_line && bot == maxy) {
1670 	GoTo(top, 0);
1671 	UpdateAttrs(blank);
1672 	TPUTS_TRACE("insert_line");
1673 	putp(insert_line);
1674     } else if (parm_rindex && top == miny && bot == maxy) {
1675 	GoTo(top, 0);
1676 	UpdateAttrs(blank);
1677 	TPUTS_TRACE("parm_rindex");
1678 	tputs(TPARM_2(parm_rindex, n, 0), n, _nc_outch);
1679     } else if (parm_insert_line && bot == maxy) {
1680 	GoTo(top, 0);
1681 	UpdateAttrs(blank);
1682 	TPUTS_TRACE("parm_insert_line");
1683 	tputs(TPARM_2(parm_insert_line, n, 0), n, _nc_outch);
1684     } else if (scroll_reverse && top == miny && bot == maxy) {
1685 	GoTo(top, 0);
1686 	UpdateAttrs(blank);
1687 	for (i = 0; i < n; i++) {
1688 	    TPUTS_TRACE("scroll_reverse");
1689 	    putp(scroll_reverse);
1690 	}
1691     } else if (insert_line && bot == maxy) {
1692 	GoTo(top, 0);
1693 	UpdateAttrs(blank);
1694 	for (i = 0; i < n; i++) {
1695 	    TPUTS_TRACE("insert_line");
1696 	    putp(insert_line);
1697 	}
1698     } else
1699 	return ERR;
1700 
1701 #if NCURSES_EXT_FUNCS
1702     if (FILL_BCE()) {
1703 	int j;
1704 	for (i = 0; i < n; i++) {
1705 	    GoTo(top + i, 0);
1706 	    for (j = 0; j < screen_columns; j++)
1707 		PutChar(CHREF(blank));
1708 	}
1709     }
1710 #endif
1711     return OK;
1712 }
1713 
1714 /* scroll by using delete_line at del and insert_line at ins */
1715 /* n > 0 */
1716 static int
1717 scroll_idl(int n, int del, int ins, NCURSES_CH_T blank)
1718 {
1719     int i;
1720 
1721     if (!((parm_delete_line || delete_line) && (parm_insert_line || insert_line)))
1722 	return ERR;
1723 
1724     GoTo(del, 0);
1725     UpdateAttrs(blank);
1726     if (n == 1 && delete_line) {
1727 	TPUTS_TRACE("delete_line");
1728 	putp(delete_line);
1729     } else if (parm_delete_line) {
1730 	TPUTS_TRACE("parm_delete_line");
1731 	tputs(TPARM_2(parm_delete_line, n, 0), n, _nc_outch);
1732     } else {			/* if (delete_line) */
1733 	for (i = 0; i < n; i++) {
1734 	    TPUTS_TRACE("delete_line");
1735 	    putp(delete_line);
1736 	}
1737     }
1738 
1739     GoTo(ins, 0);
1740     UpdateAttrs(blank);
1741     if (n == 1 && insert_line) {
1742 	TPUTS_TRACE("insert_line");
1743 	putp(insert_line);
1744     } else if (parm_insert_line) {
1745 	TPUTS_TRACE("parm_insert_line");
1746 	tputs(TPARM_2(parm_insert_line, n, 0), n, _nc_outch);
1747     } else {			/* if (insert_line) */
1748 	for (i = 0; i < n; i++) {
1749 	    TPUTS_TRACE("insert_line");
1750 	    putp(insert_line);
1751 	}
1752     }
1753 
1754     return OK;
1755 }
1756 
1757 /*
1758  * Note:  some terminals require the cursor to be within the scrolling margins
1759  * before setting them.  Generally, the cursor must be at the appropriate end
1760  * of the scrolling margins when issuing an indexing operation (it is not
1761  * apparent whether it must also be at the left margin; we do this just to be
1762  * safe).  To make the related cursor movement a little faster, we use the
1763  * save/restore cursor capabilities if the terminal has them.
1764  */
1765 NCURSES_EXPORT(int)
1766 _nc_scrolln(int n, int top, int bot, int maxy)
1767 /* scroll region from top to bot by n lines */
1768 {
1769     NCURSES_CH_T blank = ClrBlank(stdscr);
1770     int i;
1771     bool cursor_saved = FALSE;
1772     int res;
1773 
1774     TR(TRACE_MOVE, ("mvcur_scrolln(%d, %d, %d, %d)", n, top, bot, maxy));
1775 
1776 #if USE_XMC_SUPPORT
1777     /*
1778      * If we scroll, we might remove a cookie.
1779      */
1780     if (magic_cookie_glitch > 0) {
1781 	return (ERR);
1782     }
1783 #endif
1784 
1785     if (n > 0) {		/* scroll up (forward) */
1786 	/*
1787 	 * Explicitly clear if stuff pushed off top of region might
1788 	 * be saved by the terminal.
1789 	 */
1790 	res = scroll_csr_forward(n, top, bot, 0, maxy, blank);
1791 
1792 	if (res == ERR && change_scroll_region) {
1793 	    if ((((n == 1 && scroll_forward) || parm_index)
1794 		 && (SP->_cursrow == bot || SP->_cursrow == bot - 1))
1795 		&& save_cursor && restore_cursor) {
1796 		cursor_saved = TRUE;
1797 		TPUTS_TRACE("save_cursor");
1798 		putp(save_cursor);
1799 	    }
1800 	    TPUTS_TRACE("change_scroll_region");
1801 	    putp(TPARM_2(change_scroll_region, top, bot));
1802 	    if (cursor_saved) {
1803 		TPUTS_TRACE("restore_cursor");
1804 		putp(restore_cursor);
1805 	    } else {
1806 		SP->_cursrow = SP->_curscol = -1;
1807 	    }
1808 
1809 	    res = scroll_csr_forward(n, top, bot, top, bot, blank);
1810 
1811 	    TPUTS_TRACE("change_scroll_region");
1812 	    putp(TPARM_2(change_scroll_region, 0, maxy));
1813 	    SP->_cursrow = SP->_curscol = -1;
1814 	}
1815 
1816 	if (res == ERR && _nc_idlok)
1817 	    res = scroll_idl(n, top, bot - n + 1, blank);
1818 
1819 	/*
1820 	 * Clear the newly shifted-in text.
1821 	 */
1822 	if (res != ERR
1823 	    && (non_dest_scroll_region || (memory_below && bot == maxy))) {
1824 	    static const NCURSES_CH_T blank2 = NewChar(BLANK_TEXT);
1825 	    if (bot == maxy && clr_eos) {
1826 		GoTo(bot - n + 1, 0);
1827 		ClrToEOS(blank2);
1828 	    } else {
1829 		for (i = 0; i < n; i++) {
1830 		    GoTo(bot - i, 0);
1831 		    ClrToEOL(blank2, FALSE);
1832 		}
1833 	    }
1834 	}
1835 
1836     } else {			/* (n < 0) - scroll down (backward) */
1837 	res = scroll_csr_backward(-n, top, bot, 0, maxy, blank);
1838 
1839 	if (res == ERR && change_scroll_region) {
1840 	    if (top != 0 && (SP->_cursrow == top || SP->_cursrow == top - 1)
1841 		&& save_cursor && restore_cursor) {
1842 		cursor_saved = TRUE;
1843 		TPUTS_TRACE("save_cursor");
1844 		putp(save_cursor);
1845 	    }
1846 	    TPUTS_TRACE("change_scroll_region");
1847 	    putp(TPARM_2(change_scroll_region, top, bot));
1848 	    if (cursor_saved) {
1849 		TPUTS_TRACE("restore_cursor");
1850 		putp(restore_cursor);
1851 	    } else {
1852 		SP->_cursrow = SP->_curscol = -1;
1853 	    }
1854 
1855 	    res = scroll_csr_backward(-n, top, bot, top, bot, blank);
1856 
1857 	    TPUTS_TRACE("change_scroll_region");
1858 	    putp(TPARM_2(change_scroll_region, 0, maxy));
1859 	    SP->_cursrow = SP->_curscol = -1;
1860 	}
1861 
1862 	if (res == ERR && _nc_idlok)
1863 	    res = scroll_idl(-n, bot + n + 1, top, blank);
1864 
1865 	/*
1866 	 * Clear the newly shifted-in text.
1867 	 */
1868 	if (res != ERR
1869 	    && (non_dest_scroll_region || (memory_above && top == 0))) {
1870 	    static const NCURSES_CH_T blank2 = NewChar(BLANK_TEXT);
1871 	    for (i = 0; i < -n; i++) {
1872 		GoTo(i + top, 0);
1873 		ClrToEOL(blank2, FALSE);
1874 	    }
1875 	}
1876     }
1877 
1878     if (res == ERR)
1879 	return (ERR);
1880 
1881     _nc_scroll_window(curscr, n, top, bot, blank);
1882 
1883     /* shift hash values too - they can be reused */
1884     _nc_scroll_oldhash(n, top, bot);
1885 
1886     return (OK);
1887 }
1888 
1889 NCURSES_EXPORT(void)
1890 _nc_screen_resume(void)
1891 {
1892     /* make sure terminal is in a sane known state */
1893     SetAttr(SCREEN_ATTRS(SP), A_NORMAL);
1894     newscr->_clear = TRUE;
1895 
1896     /* reset color pairs and definitions */
1897     if (SP->_coloron || SP->_color_defs)
1898 	_nc_reset_colors();
1899 
1900     /* restore user-defined colors, if any */
1901     if (SP->_color_defs < 0) {
1902 	int n;
1903 	SP->_color_defs = -(SP->_color_defs);
1904 	for (n = 0; n < SP->_color_defs; ++n) {
1905 	    if (SP->_color_table[n].init) {
1906 		init_color(n,
1907 			   SP->_color_table[n].r,
1908 			   SP->_color_table[n].g,
1909 			   SP->_color_table[n].b);
1910 	    }
1911 	}
1912     }
1913 
1914     if (exit_attribute_mode)
1915 	putp(exit_attribute_mode);
1916     else {
1917 	/* turn off attributes */
1918 	if (exit_alt_charset_mode)
1919 	    putp(exit_alt_charset_mode);
1920 	if (exit_standout_mode)
1921 	    putp(exit_standout_mode);
1922 	if (exit_underline_mode)
1923 	    putp(exit_underline_mode);
1924     }
1925     if (exit_insert_mode)
1926 	putp(exit_insert_mode);
1927     if (enter_am_mode && exit_am_mode)
1928 	putp(auto_right_margin ? enter_am_mode : exit_am_mode);
1929 }
1930 
1931 NCURSES_EXPORT(void)
1932 _nc_screen_init(void)
1933 {
1934     _nc_screen_resume();
1935 }
1936 
1937 /* wrap up screen handling */
1938 NCURSES_EXPORT(void)
1939 _nc_screen_wrap(void)
1940 {
1941     UpdateAttrs(normal);
1942 #if NCURSES_EXT_FUNCS
1943     if (SP->_coloron
1944 	&& !SP->_default_color) {
1945 	static const NCURSES_CH_T blank = NewChar(BLANK_TEXT);
1946 	SP->_default_color = TRUE;
1947 	_nc_do_color(-1, 0, FALSE, _nc_outch);
1948 	SP->_default_color = FALSE;
1949 
1950 	mvcur(SP->_cursrow, SP->_curscol, screen_lines - 1, 0);
1951 
1952 	ClrToEOL(blank, TRUE);
1953     }
1954 #endif
1955     if (SP->_color_defs) {
1956 	_nc_reset_colors();
1957     }
1958 }
1959 
1960 #if USE_XMC_SUPPORT
1961 NCURSES_EXPORT(void)
1962 _nc_do_xmc_glitch(attr_t previous)
1963 {
1964     attr_t chg = XMC_CHANGES(previous ^ AttrOf(SCREEN_ATTRS(SP)));
1965 
1966     while (chg != 0) {
1967 	if (chg & 1) {
1968 	    SP->_curscol += magic_cookie_glitch;
1969 	    if (SP->_curscol >= SP->_columns)
1970 		wrap_cursor();
1971 	    TR(TRACE_UPDATE, ("bumped to %d,%d after cookie", SP->_cursrow, SP->_curscol));
1972 	}
1973 	chg >>= 1;
1974     }
1975 }
1976 #endif /* USE_XMC_SUPPORT */
1977